Telecommunication network operators are upgrading their optical backbones to Optical Transport Networks (OTN) based on the International Telecommunications Union ITU-T G.709 hierarchy. OTN has been used for Dense Wavelength Division Multiplexed (DWDM) point-to-point links and is now being extended to larger scale networks comprising DWDM links, OTN cross-connects and other transmission equipment.
One way of evolving the currently deployed OTN point-to-point links to implement an optical switched network is to add OTN cross-connects to the existing DWDM equipment. The OTN cross-connects switch at the level of Optical Channel Data Units (ODUk). An operator typically has the options of either using DWDM equipments and OTN cross-connects from a single vendor or using DWDM equipments and OTN cross-connects from different vendors. The provision of two separate network equipments can cause issues in terms of alarm generation and reporting when a defect occurs on an optical link, particularly when the separate network equipments are provided by different vendors.